Almost identical functionality to ReKey is built into Panther. Look in System Preferences -> Keyboard & Mouse -> Keyboard shortcuts. Just like ReKey, you have to choose to add a shortcut, then manually type in the text of the menu item you want to assign a keyboard shortcut to. It's almost as if Apple copied ReKey's source code, except the interfaces are so rudimentary that you can see how the two came to the same place. In any case, anyone running 10.3.x does not need ReKey. But if you're on an older OS X, ReKey works and is recommended.